Electrical insect exterminating devices using a grid or screen of electrically conducting lines of opposite polarity are described for example in the Marsel U.S. Pat. No. 1,953,622; the Zalesky U.S. Pat. No. 2,188,618; the Sykes U.S. Pat. No. 1,966,999; the Bowman U.S. Pat. No. 1,972,180; the Springer U.S. Pat. No. 4,037,351; and the Hudgin U.S. Pat. No. 4,300,306. An insect entering or encountering the grid or screen is electrocuted. These devices, however, are designed for application to flying insects and furthermore are generally operated using standard AC line voltage or greater voltage.
An example of the now familiar hanging lantern or light source and grid type device for electrocuting flying insects is described in the DeYoreo U.S. Pat. No. 4,523,404. These hanging light source and grid devices are operated by conventional AC power line voltage sources. Another flying insect electrocuting screen or grid for permanent installation for example between farm building rafters or wall posts is described in the Partridge U.S. Pat. No. 2,912,787.
For crawling pests the prior art references generally describe a variety of traps designed for particular applications such as rodents, for example, as set forth in the Tidwell U.S. Pat. No. 4,074,456: worms, for example, as set forth in the Fancy U.S. Pat. No. 4,241,532; and cockroaches, for example, as set forth in the Darncharnjitt U.S. Pat. No. 4,144,668. A disadvantage of these trap devices is the complexity of mechanical and electrical structure.
A further disadvantage of the prior art electrical exterminating devices and traps is that they are not well adapted for guarding an area to be protected from crawling slugs and pests, such as a garden or bed of plants. The disclosed structures cannot provide continuous protection along the boundary of such an area.